Techniques for retransmissions in wireless communication systems

ABSTRACT

Aspects described herein relate to retransmission implementations in new radio (NR) wireless communication systems. In one aspect, a network entity may initially perform a multicast transmission and then a multicast retransmission according to a hybrid automatic repeat request (HARQ) process. In another aspect, a user equipment (UE) may initially receive a multicast transmission from a network entity and a subsequent multicast transmission according to a HARQ process. In an additional aspect, a network entity may initially perform a multicast transmission and then a subsequent unicast retransmission according to a HARQ process. In yet another aspect, a UE may initially receive a multicast transmission from a network entity and a subsequent unicast transmission according to a HARQ process.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional Application Ser.No. 62/879,043, entitled “TECHNIQUES FOR RETRANSMISSIONS IN WIRELESSCOMMUNICATION SYSTEMS” and filed on Jul. 26, 2019, which is expresslyincorporated by reference herein in its entirety.

BACKGROUND

Aspects of the present disclosure relate generally to wirelesscommunication systems, and more particularly, to retransmission aspectsin new radio (NR) multicast.

Wireless communication systems are widely deployed to provide varioustypes of communication content such as voice, video, packet data,messaging, broadcast, and so on. These systems may be multiple-accesssystems capable of supporting communication with multiple users bysharing the available system resources (e.g., time, frequency, andpower). Examples of such multiple-access systems include code-divisionmultiple access (CDMA) systems, time-division multiple access (TDMA)systems, frequency-division multiple access (FDMA) systems, andorthogonal frequency-division multiple access (OFDMA) systems, andsingle-carrier frequency division multiple access (SC-FDMA) systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. For example, a fifth generation (5G)wireless communications technology (which can be referred to as NR) isenvisaged to expand and support diverse usage scenarios and applicationswith respect to current mobile network generations. In an aspect, 5Gcommunications technology can include: enhanced mobile broadbandaddressing human-centric use cases for access to multimedia content,services and data; ultra-reliable-low latency communications (URLLC)with certain specifications for latency and reliability; and massivemachine type communications, which can allow a very large number ofconnected devices and transmission of a relatively low volume ofnon-delay-sensitive information.

For example, for various communications technology such as, but notlimited to NR, mixed mode changes may increase transmission speed andflexibility but also retransmission complexity. Thus, improvements inwireless communication operations may be desired.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

According to an example, a method of wireless communication at a networkentity is provided. The method may include transmitting first multicastdata to a plurality of user equipments (UEs) on at least one downlinkcommunication channel. The method may further include receiving, on anuplink communication channel, a negative acknowledgement (NACK) from oneor more UEs from the plurality of UEs in response to the first multicastdata transmission. The method may further include transmitting secondmulticast data including at least a portion of the first multicast datato the one or more UEs according to a hybrid automatic repeat request(HARQ) process.

In a further aspect, the present disclosure includes an apparatus forwireless communication including a memory and at least one processorcoupled to the memory. The at least one processor may be configured totransmit first multicast data to a plurality of UEs on at least onedownlink communication channel. The at least one processor may furtherbe configured to receive, on an uplink communication channel, a NACKfrom one or more UEs from the plurality of UEs in response to the firstmulticast data transmission. The at least one processor may further beconfigured to transmit second multicast data including at least aportion of the first multicast data to the one or more UEs according toa HARQ process.

In an additional aspect, the present disclosure includes an apparatusfor wireless communication including means for transmitting firstmulticast data to a plurality of UEs on at least one downlinkcommunication channel. The apparatus may further include means forreceiving, on an uplink communication channel, a NACK from one or moreUEs from the plurality of UEs in response to the first multicast datatransmission. The apparatus may further include means for transmittingsecond multicast data including at least a portion of the firstmulticast data to the one or more UEs according to a HARQ process.

In yet another aspect, the present disclosure includes a non-transitorycomputer-readable medium storing computer executable code, the code whenexecuted by a processor cause the processor to transmit first multicastdata to a plurality of UEs on at least one downlink communicationchannel. The non-transitory computer-readable medium may further includecode when executed by a processor cause the processor to receive, on anuplink communication channel, a NACK from one or more UEs from theplurality of UEs in response to the first multicast data transmission,and transmit second multicast data including at least a portion of thefirst multicast data to the one or more UEs according to a HARQ process.

According to another example, a method of wireless communication at a UEis provided. The method may include receiving, on a downlinkcommunication channel from a network entity, first multicast data from anetwork entity. The method may further include determining that at leasta portion of data from the first multicast data has not been received.The method may further include transmitting, on an uplink communicationchannel to the network entity, a NACK to the network entity according toa HARQ process in response to determining that at least the portion ofthe data has not been received. The method may further include receivingsecond multicast data including at least the first multicast portion ofthe data according to the HARQ process in response to transmitting theNACK to the network entity.

In a further aspect, the present disclosure includes an apparatus forwireless communication including a memory and at least one processorcoupled to the memory. The at least one processor may be configured toreceive, on a downlink communication channel from a network entity,first multicast data from a network entity. The at least one processormay be configured to determine that at least a portion of data from thefirst multicast data has not been received. The at least one processormay be configured to transmit, on an uplink communication channel to thenetwork entity, a NACK to the network entity according to a HARQ processin response to determining that at least the portion of the data has notbeen received. The at least one processor may be configured to receivesecond multicast data including at least the first multicast portion ofthe data according to the HARQ process in response to transmitting theNACK to the network entity.

In an additional aspect, the present disclosure includes an apparatusfor wireless communication including means for receiving, on a downlinkcommunication channel from a network entity, first multicast data from anetwork entity. The apparatus may further include means for determiningthat at least a portion of data from the first multicast data has notbeen received. The apparatus may further include means for transmitting,on an uplink communication channel to the network entity, a NACK to thenetwork entity according to a HARQ process in response to determiningthat at least the portion of the data has not been received. Theapparatus may further include means for receiving second multicast dataincluding at least the first multicast portion of the data according tothe HARQ process in response to transmitting the NACK to the networkentity.

In yet another aspect, the present disclosure includes a non-transitorycomputer-readable medium storing computer executable code, the code whenexecuted by a processor cause the processor to receive, on a downlinkcommunication channel from a network entity, first multicast data from anetwork entity. The non-transitory computer-readable medium may furtherinclude code when executed by a processor cause the processor todetermine that at least a portion of data from the first multicast datahas not been received, transmit, on an uplink communication channel tothe network entity, a NACK to the network entity according to a HARQprocess in response to determining that at least the portion of the datahas not been received, and receive second multicast data including atleast the first multicast portion of the data according to the HARQprocess in response to transmitting the NACK to the network entity.

According to an example, a method of wireless communication at a networkentity is provided. The method may include transmitting multicast datato a plurality of UEs on at least one downlink communication channel.The method may further include receiving, on an uplink communicationchannel, a NACK from at least one UE of the plurality of UEs in responseto the multicast data transmission. The method may further includetransmitting unicast data including at least a portion of the multicastdata according to a HARQ process to the at least one UE.

In a further aspect, the present disclosure includes an apparatus forwireless communication including a memory and at least one processorcoupled to the memory. The at least one processor may be configured totransmit multicast data to a plurality of UEs on at least one downlinkcommunication channel. The at least one processor may be configured toreceive, on an uplink communication channel, a NACK from at least one UEof the plurality of UEs in response to the multicast data transmission.The at least one processor may be configured to transmit unicast dataincluding at least a portion of the multicast data according to a HARQprocess to the at least one UE.

In an additional aspect, the present disclosure includes an apparatusfor wireless communication including means for transmitting multicastdata to a plurality of UEs on at least one downlink communicationchannel. The apparatus may further include means for receiving, on anuplink communication channel, a NACK from at least one UE of theplurality of UEs in response to the multicast data transmission. Theapparatus may further include means for transmitting unicast dataincluding at least a portion of the multicast data according to a HARQprocess to the at least one UE.

In yet another aspect, the present disclosure includes a non-transitorycomputer-readable medium storing computer executable code, the code whenexecuted by a processor cause the processor to transmit multicast datato a plurality of UEs on at least one downlink communication channel.The non-transitory computer-readable medium may further include codewhen executed by a processor cause the processor to receive, on anuplink communication channel, a NACK from at least one UE of theplurality of UEs in response to the multicast data transmission, andtransmit unicast data including at least a portion of the multicast dataaccording to a HARQ process to the at least one UE.

According to another example, a method of wireless communication at a UEis provided. The method may include receiving, on a downlinkcommunication channel from a network entity, multicast data from anetwork entity. The method may further include determining that at leasta portion of data from the multicast data has not been received via themulticast data transmission. The method may further includetransmitting, on an uplink communication channel to the network entity,a NACK to the network entity according to a HARQ process in response todetermining that at least the portion of the multicast data has not beenreceived. The method may further include receiving unicast dataincluding at least the portion of the multicast data according to theHARQ process in response to transmitting the NACK to the network entity.

In a further aspect, the present disclosure includes an apparatus forwireless communication including a memory and at least one processorcoupled to the memory. The at least one processor may be configured toreceive, on a downlink communication channel from a network entity,multicast data from a network entity. The at least one processor may beconfigured to determine that at least a portion of data from themulticast data has not been received via the multicast datatransmission. The at least one processor may be configured to transmit,on an uplink communication channel to the network entity, a NACK to thenetwork entity according to a HARQ process in response to determiningthat at least the portion of the multicast data has not been received.The at least one processor may be configured to receive unicast dataincluding at least the portion of the multicast data according to theHARQ process in response to transmitting the NACK to the network entity.

In an additional aspect, the present disclosure includes an apparatusfor wireless communication including means for receiving, on a downlinkcommunication channel from a network entity, multicast data from anetwork entity. The apparatus may further include means for determiningthat at least a portion of data from the multicast data has not beenreceived via the multicast data transmission. The apparatus may furtherinclude means for transmitting, on an uplink communication channel tothe network entity, a NACK to the network entity according to a HARQprocess in response to determining that at least the portion of themulticast data has not been received. The apparatus may further includemeans for receiving unicast data including at least the portion of themulticast data according to the HARQ process in response to transmittingthe NACK to the network entity.

In yet another aspect, the present disclosure includes a non-transitorycomputer-readable medium storing computer executable code, the code whenexecuted by a processor cause the processor to receive, on a downlinkcommunication channel from a network entity, multicast data from anetwork entity. The non-transitory computer-readable medium may furtherinclude code when executed by a processor cause the processor todetermine that at least a portion of data from the multicast data hasnot been received via the multicast data transmission, transmit, on anuplink communication channel to the network entity, a NACK to thenetwork entity according to a HARQ process in response to determiningthat at least the portion of the multicast data has not been received,and receive unicast data including at least the portion of the multicastdata according to the HARQ process in response to transmitting the NACKto the network entity.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed aspects will hereinafter be described in conjunction withthe appended drawings, provided to illustrate and not to limit thedisclosed aspects, wherein like designations denote like elements, andin which:

FIG. 1 illustrates an example of a wireless communication system, inaccordance with various aspects of the present disclosure;

FIG. 2 is a block diagram illustrating an example of a user equipment(UE), in accordance with various aspects of the present disclosure;

FIG. 3 is a block diagram illustrating an example of a network entity(also referred to as a base station), in accordance with various aspectsof the present disclosure;

FIG. 4 is a flow chart illustrating an example of a method for wirelesscommunications at a UE including an initial multicast reception andsecond multicast reception of a multicast retransmission, in accordancewith various aspects of the present disclosure;

FIG. 5 is a flow chart illustrating an example of a method for wirelesscommunications including a multicast transmission and multicastretransmission at a network entity, in accordance with various aspectsof the present disclosure;

FIG. 6 is a flow chart illustrating an example of a method for wirelesscommunications at a UE including a multicast reception and a unicastreception, in accordance with various aspects of the present disclosure;

FIG. 7 is a flow chart illustrating an example of a method for wirelesscommunications at a network entity including a multicast transmissionand a multicast retransmission, in accordance with various aspects ofthe present disclosure; and

FIG. 8 is a block diagram illustrating an example of a MIMOcommunication system including a base station and a UE, in accordancewith various aspects of the present disclosure.

DETAILED DESCRIPTION

Various aspects are now described with reference to the drawings. In thefollowing description, for purposes of explanation, numerous specificdetails are set forth in order to provide a thorough understanding ofone or more aspects. It may be evident, however, that such aspect(s) maybe practiced without these specific details.

The described features generally relate to retransmission aspects of newradio (NR) multicast transmissions. Specifically, NR may support veryhigh data rates with lower latency. NR may further support mixed modetransmissions/retransmissions. That is, in some wireless communicationsystems, a radio access network (RAN) may allow for dynamic change orswitching between multicast and unicast transmissions/retransmissions.For example, a user equipment (UE) may communicate using a dedicatedunicast service that provides two-way point-to-point communicationbetween the UE and the network (e.g., via a network entity and/or basestation). In another example, a network may communicate with multipleUEs corresponding to a multicast service. Multicast transmissions mayefficiently use spectrum resources, which may allow the same copy ofcontent to be sent to multiple UEs instead of sending multiple copies ofthe same content to multiple UEs.

For instance, NR may support a number of modes of operation whendelivering multicast traffic, also referred to as mixed mode. A firstmode may correspond to a multicast transmission and a multicastretransmission. The first mode may support retransmissions to a largenumber of UEs when the UEs failed to receive the initial transmission. Asecond mode may correspond to a multicast transmission and a unicastretransmission. The second mode may support retransmissions for a smallnumber of UEs, which in some cases may be more efficient in deliveringdata. A third mode may correspond to an initial unicast transmission anda multicast retransmission.

As part of increasing the reliability of transmissions in NR mixed mode,hybrid automatic repeat request (HARQ) retransmissions may beimplemented. For instance, as HARQ is implemented according to a lowlatency scheme in NR (i.e., in TDD), implementing HARQ retransmissionsmay increase the reliability of transmissions in NR compared to, forexample, radio link control (RLC) retransmissions. As such, a HARQprocess and/or retransmission management scheme may be desired tosupport HARQ for mixed mode NR transmissions.

In one implementation, a network entity may support multicasttransmissions and multicast retransmissions. Specifically, the networkentity may transmit first multicast data to a plurality of UEs on atleast one downlink communication channel. The network entity mayreceive, on an uplink communication channel, a negative acknowledgement(NACK) from one or more UEs from the plurality of UEs in response to thefirst multicast data transmission. The network entity may furthertransmit second multicast data including at least a portion of the firstmulticast data to the one or more UEs according to a HARQ process.

In another implementation, a UE may support multicast receptions forboth multicast transmissions and retransmissions from a network entity.Specifically, the UE may receive, on a downlink communication channelfrom a network entity, first multicast data from a network entity. TheUE may further determine that at least a portion of data from the firstmulticast data has not been received. The UE may further transmit, on anuplink communication channel to the network entity, a NACK to thenetwork entity according to a HARQ process in response to determiningthat at least the portion of the data has not been received. The UE mayfurther receive second multicast data including at least the portion ofthe first multicast data according to the HARQ process and in responseto transmitting the NACK to the network entity.

In an additional implementation, a network entity may support multicasttransmissions and unicast retransmissions. Specifically, the networkentity may transmit multicast data to a plurality of UEs on at least onedownlink communication channel. The network entity may further receive,on an uplink communication channel, a NACK from at least one UE of theplurality of UEs in response to the multicast data transmission. Thenetwork entity may further transmit unicast data including at least aportion of the multicast data according to a HARQ process to the atleast one UE.

In yet another implementation, a UE may support an initial multicastreception and a subsequent unicast reception of a unicast retransmissionby a network entity. Specifically, the UE may receive, on a downlinkcommunication channel from a network entity, multicast data from anetwork entity. The UE may determine that at least a portion of datafrom the multicast data has not been received via the multicast datatransmission. The UE may transmit, on an uplink communication channel tothe network entity, a NACK to the network entity according to a HARQprocess and in response to determining that at least the portion of themulticast data has not been received. The UE may further receive unicastdata including at least the portion of the multicast data according tothe HARQ process in response to transmitting the NACK to the networkentity.

The described features will be presented in more detail below withreference to FIGS. 1-8 .

As used in this application, the terms “component,” “module,” “system”and the like are intended to include a computer-related entity, such asbut not limited to hardware, software, a combination of hardware andsoftware, or software in execution. For example, a component may be, butis not limited to being, a process running on a processor, a processor,an object, an executable, a thread of execution, a program, and/or acomputer. By way of illustration, both an application running on acomputing device and the computing device can be a component. One ormore components can reside within a process and/or thread of executionand a component can be localized on one computer and/or distributedbetween two or more computers. In addition, these components can executefrom various computer readable media having various data structuresstored thereon. The components can communicate by way of local and/orremote processes such as in accordance with a signal having one or moredata packets, such as data from one component interacting with anothercomponent in a local system, distributed system, and/or across a networksuch as the Internet with other systems by way of the signal. Softwareshall be construed broadly to mean instructions, instruction sets, code,code segments, program code, programs, subprograms, software modules,applications, software applications, software packages, routines,subroutines, objects, executables, threads of execution, procedures,functions, etc., whether referred to as software, firmware, middleware,microcode, hardware description language, or otherwise.

Techniques described herein may be used for various wirelesscommunication systems such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, andother systems. The terms “system” and “network” may often be usedinterchangeably. A CDMA system may implement a radio technology such asCDMA2000, Universal Terrestrial Radio Access (UTRA), etc. CDMA2000covers IS-2000, IS-95, and IS-856 standards. IS-2000 Releases 0 and Aare commonly referred to as CDMA2000 1×, 1×, etc. IS-856 (TIA-856) iscommonly referred to as CDMA2000 1×EV-DO, High Rate Packet Data (HRPD),etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. ATDMA system may implement a radio technology such as Global System forMobile Communications (GSM). An OFDMA system may implement a radiotechnology such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA),IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM™, etc.UTRA and E-UTRA are part of Universal Mobile Telecommunication System(UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are newreleases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, andGSM are described in documents from an organization named “3rdGeneration Partnership Project” (3GPP). CDMA2000 and UMB are describedin documents from an organization named “3rd Generation PartnershipProject 2” (3GPP2). The techniques described herein may be used for thesystems and radio technologies mentioned above as well as other systemsand radio technologies, including cellular (e.g., LTE) communicationsover a shared radio frequency spectrum band. The description below,however, describes an LTE/LTE-A system for purposes of example, and LTEterminology is used in much of the description below, although thetechniques are applicable beyond LTE/LTE-A applications (e.g., to fifthgeneration (5G) NR networks or other next generation communicationsystems).

The following description provides examples, and is not limiting of thescope, applicability, or examples set forth in the claims. Changes maybe made in the function and arrangement of elements discussed withoutdeparting from the scope of the disclosure. Various examples may omit,substitute, or add various procedures or components as appropriate. Forinstance, the methods described may be performed in an order differentfrom that described, and various steps may be added, omitted, orcombined. Also, features described with respect to some examples may becombined in other examples.

Various aspects or features will be presented in terms of systems thatcan include a number of devices, components, modules, and the like. Itis to be understood and appreciated that the various systems can includeadditional devices, components, modules, etc. and/or may not include allof the devices, components, modules etc. discussed in connection withthe figures. A combination of these approaches can also be used.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network 100. The wireless communications system(also referred to as a wireless wide area network (WWAN)) can includebase stations 102, UEs 104, an Evolved Packet Core (EPC) 160, and/or a5G Core (5GC) 190. The base stations 102, which may also be referred toas network entities, may include macro cells (high power cellular basestation) and/or small cells (low power cellular base station). The macrocells can include base stations. The small cells can include femtocells,picocells, and microcells. In an example, the base stations 102 may alsoinclude gNBs 180, as described further herein. In one example, somenodes such as UE 104 of the wireless communication system may have amodem 240 and communicating component 242 for performing HARQ processesbased on missing multicast data received from the base station 102/gNB180, as described herein. In addition, some nodes such as base station102 may have a modem 340 and retransmission component 342 forfacilitating HARQ multicast and unicast transmissions andretransmissions, as described herein. Though a UE 104 is shown as havingthe modem 240 and communicating component 242 and a base station 102/gNB180 is shown as having the modem 340 and retransmission component 342,this is one illustrative example, and substantially any node or type ofnode may include a modem 240 and communicating component 242 and/or amodem 340 and retransmission component 342 for providing correspondingfunctionalities described herein.

For example, in one implementation, both the base stations 102, whichinclude the retransmission component 342, and UEs 104, which include thecommunication component 242, may support multicast transmissions andmulticast retransmissions (e.g., first mode). Specifically, thearrangement of a number of HARQ processes used for multicast may beconfigured. This configuration may be common across all UEs 104 in thesame multicast group (i.e., monitoring the same group radio networktemporary identifier (G-RNTI)). The same procedures as unicasttransmissions and retransmissions may apply in this case (with respectto a new data indicator (NDI), HARQ identifier (ID), etc.).

A number of implementations may be provided regarding support for atotal number of unicast plus multicast/broadcast HARQ processes. In afirst aspect of the first mode, a disjoint set of HARQ processes may beprovided such that the UE 104 may be able to keep track of bothmulticast and unicast HARQ processes. There may be a limitation on thetotal number of HARQ processes per serving cell (e.g., unicast plusmulticast HARQ processes). In one aspect, the limitation may be based ona configuration, e.g., a total number of configured unicast plusconfigured multicast HARQ processes satisfying a threshold limit value(e.g., less than or equal to the threshold limit value). In anotheraspect, the number of HARQ processes for unicast may be configured (e.g.16), and then separately the number of HARQ processes for multicast maybe configured (e.g. 4). The HARQ processes for multicast may be takenfrom the unicast (e.g. the UE 104 may not be expected to be scheduledwith HARQ processes 11 . . . 15 with this configuration).

In a second aspect of the first mode, HARQ processes may be sharedacross multicast and unicast transmissions. For example, the basestations 102 (e.g., eNB) may keep track of the UEs 104 that arereceiving multicast data, and subsequently dynamically reuse themulticast/broadcast HARQ processes when they are not being used forunicast. An NDI may be used when switching between unicast andbroadcast. Further, for each active HARQ process, the UE 104 may storewhether the transport block (TB) corresponds to a unicast or multicasttransmission.

The base station 102 and/or UE 104 may also separately store the NDI forunicast and multicast. For instance, storing such data may be useful atthe base station 102 to protect against the case where the UE 104 maymiss a downlink control information (DCI). At the UE 104, if a new grantis received, the communicating component 242 may clear a buffer andconsider a NDI to be toggled (e.g., corresponding to a new TB) if andwhen the grant is for unicast/broadcast and the stored TB is forbroadcast/unicast. In some aspects, the HARQ process identifierrelationship may be one of direct or indirect. A direct relationship maycorrespond to the case where HARQ process identifier for broadcastoverrides the same HARQ process identifier for unicast. An indirectrelationship may correspond to the case where HARQ process identifierfor broadcast overrides a different HARQ process identifier for unicast(i.e., translation function may be signaled to UE and specified).

In a further implementation, unicast retransmissions may be supportedfollowing initial multicast transmissions (e.g., second mode). In suchimplementation, an association of multicast HARQ processes with unicastHARQ processes may be made. In one aspect, a unicast grant may bereceived with a cell radio network temporary identifier (C-RNTI),including an association between the unicast HARQ process and multicastHARQ process. For example, if the UE 104 is configured with M=3 HARQprocesses for unicast, and N=2 HARQ processes for multicast, the firstM−N=1 may be dedicated to unicast, and the remaining N can be used formulticast retransmissions. In another example, broadcast HARQ processes{0,1} may correspond to unicast HARQ processes {10, 11} in one UE and{7, 8} in a different UE.

Further, when the UE 104 receives a unicast HARQ retransmission afterinitial broadcast/multicast transmission, the UE 104 may combine loglikelihood ratios (LLRs) before attempting the decoding. At the UE 104,if a new grant is received, the communicating component 242 may clear abuffer and consider a NDI to be toggled (e.g., corresponding to a newTB) if and when the grant is for multicast/broadcast and the stored TBis for unicast. In such case, the TB mode may correspond tomulticast/broadcast. On the other hand, if a new grant is received, thecommunicating component 242 may combine data if and when the grant isfor unicast and the stored TB is for broadcast. In such case, the TBmode may correspond to unicast.

In another aspect, a unicast grant may be received with a third RNTI(e.g. retransmission radio network temporary identifier (RETX-RNTI))which may indicate that the retransmission is a unicast retransmissionassociated with a multicast DCI. In some aspects, the same HARQ processmay be reused.

In an additional aspect, retransmissions may be performed with groupRNTI (G-RNTI), but the DCI may be mapped onto the UE-specific searchspace (USS) (e.g., instead of common search space). Size would followUSS. The HARQ/NDI may be shared with the G-RNTI CSS DCI. In this case,by base station 102 implementation, the PDCCH can be unicast (e.g., sentin USS) but multiple PDCCH for different UEs may point to the samePDSCH.

In another aspect, a number of benefits of switching to unicast comparedto multicast may exist. For instance, UE-specific CSI feedback may beutilized to optimize transmission for a particular UE. Further,UE-specific configuration (more flexibility in DCI) may be utilized. Inan example operating within frequency range 1, there may be two UEs 104with NACK'ed transmissions. The base station 102 may be configured touse UE-specific transmission to transmit using PRB 0-10 to UE1 (e.g.,using precoding/CSI optimized for a first UE) and transmit using PRB50-60 to UE2 (e.g., using precoding/CSI optimized for a second UE). Inthe baseline setting, UEX may receive the transmission for UEX, but theperformance may be better if the first UE also receives the transmissionfor the second UE.

Hence, for multiple G-RNTI transmissions in one transmit time interval(TTI), a UE 104 may select which one to decode. That is, there may bemultiple DCIs associated with the same G-RNTI (or with C-RNTI), but notmultiple G-RNTI. The UE may determine which PDSCH to decode (e.g., basedon a determined DMRS signal-to-noise ratio (SNR)). In a further aspect,since a low density parity check (LDPC) decoding quantity may notincrease, a UE capability may be added to enable decoding of multipleDCIs associated with the same TB. For instance, the DCIs may all beG-RNTI, or mix of G-RNTI/C-RNTI. Another implementation may allow for asingle DCI with more than two clusters (e.g., optimized for greater thantwo UEs) and with separate parameters (e.g., potentially modulation andcoding scheme (MCS)/code rate matching may be performed separately).

The base stations 102 configured for 4G LTE (which can collectively bereferred to as Evolved Universal Mobile Telecommunications System (UMTS)Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC160 through backhaul links 132 (e.g., using an S1 interface). The basestations 102 configured for 5G NR (which can collectively be referred toas Next Generation RAN (NG-RAN)) may interface with 5GC 190 throughbackhaul links 184. In addition to other functions, the base stations102 may perform one or more of the following functions: transfer of userdata, radio channel ciphering and deciphering, integrity protection,header compression, mobility control functions (e.g., handover, dualconnectivity), inter-cell interference coordination, connection setupand release, load balancing, distribution for non-access stratum (NAS)messages, NAS node selection, synchronization, radio access network(RAN) sharing, multimedia broadcast multicast service (MBMS), subscriberand equipment trace, RAN information management (RIM), paging,positioning, and delivery of warning messages. The base stations 102 maycommunicate directly or indirectly (e.g., through the EPC 160 or 5GC190) with each other over backhaul links 134 (e.g., using an X2interface). The backhaul links 132, 134 and/or 184 may be wired orwireless.

The base stations 102 may wirelessly communicate with one or more UEs104. Each of the base stations 102 may provide communication coveragefor a respective geographic coverage area 110. There may be overlappinggeographic coverage areas 110. For example, the small cell 102′ may havea coverage area 110′ that overlaps the coverage area 110 of one or moremacro base stations 102. A network that includes both small cell andmacro cells may be referred to as a heterogeneous network. Aheterogeneous network may also include Home Evolved Node Bs (eNBs)(HeNBs), which may provide service to a restricted group, which can bereferred to as a closed subscriber group (CSG). The communication links120 between the base stations 102 and the UEs 104 may include uplink(UL) (also referred to as reverse link) transmissions from a UE 104 to abase station 102 and/or downlink (DL) (also referred to as forward link)transmissions from a base station 102 to a UE 104. The communicationlinks 120 may use multiple-input and multiple-output (MIMO) antennatechnology, including spatial multiplexing, beamforming, and/or transmitdiversity. The communication links may be through one or more carriers.The base stations 102/UEs 104 may use spectrum up to Y MHz (e.g., 5, 10,15, 20, 100, 400, etc. MHz) bandwidth per carrier allocated in a carrieraggregation of up to a total of Yx MHz (e.g., for x component carriers)used for transmission in the DL and/or the UL direction. The carriersmay or may not be adjacent to each other. Allocation of carriers may beasymmetric with respect to DL and UL (e.g., more or less carriers may beallocated for DL than for UL). The component carriers may include aprimary component carrier and one or more secondary component carriers.A primary component carrier may be referred to as a primary cell (PCell)and a secondary component carrier may be referred to as a secondary cell(SCell).

In another example, certain UEs 104 may communicate with each otherusing device-to-device (D2D) communication link 158. The D2Dcommunication link 158 may use the DL/UL WWAN spectrum. The D2Dcommunication link 158 may use one or more sidelink channels, such as aphysical sidelink broadcast channel (PSBCH), a physical sidelinkdiscovery channel (PSDCH), a physical sidelink shared channel (PSSCH),and a physical sidelink control channel (PSCCH). D2D communication maybe through a variety of wireless D2D communications systems, such as forexample, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi accesspoint (AP) 150 in communication with Wi-Fi stations (STAs) 152 viacommunication links 154 in a 5 GHz unlicensed frequency spectrum. Whencommunicating in an unlicensed frequency spectrum, the STAs 152/AP 150may perform a clear channel assessment (CCA) prior to communicating inorder to determine whether the channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensedfrequency spectrum. When operating in an unlicensed frequency spectrum,the small cell 102′ may employ NR and use the same 5 GHz unlicensedfrequency spectrum as used by the Wi-Fi AP 150. The small cell 102′,employing NR in an unlicensed frequency spectrum, may boost coverage toand/or increase capacity of the access network.

A base station 102, whether a small cell 102′ or a large cell (e.g.,macro base station), may include an eNB, gNodeB (gNB), or other type ofbase station. Some base stations, such as gNB 180 may operate in atraditional sub 6 GHz spectrum, in millimeter wave (mmW) frequencies,and/or near mmW frequencies in communication with the UE 104. When thegNB 180 operates in mmW or near mmW frequencies, the gNB 180 may bereferred to as an mmW base station. Extremely high frequency (EHF) ispart of the RF in the electromagnetic spectrum. EHF has a range of 30GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters.Radio waves in the band may be referred to as a millimeter wave. NearmmW may extend down to a frequency of 3 GHz with a wavelength of 100millimeters. The super high frequency (SHF) band extends between 3 GHzand 30 GHz, also referred to as centimeter wave. Communications usingthe mmW/near mmW radio frequency band has extremely high path loss and ashort range. The mmW base station 180 may utilize beamforming 182 withthe UE 104 to compensate for the extremely high path loss and shortrange. A base station 102 referred to herein can include a gNB 180.

The EPC 160 may include a Mobility Management Entity (MME) 162, otherMMEs 164, a Serving Gateway 166, a Multimedia Broadcast MulticastService (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC)170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may be incommunication with a Home Subscriber Server (HSS) 174. The MME 162 isthe control node that processes the signaling between the UEs 104 andthe EPC 160. Generally, the MME 162 provides bearer and connectionmanagement. All user Internet protocol (IP) packets are transferredthrough the Serving Gateway 166, which itself is connected to the PDNGateway 172. The PDN Gateway 172 provides UE IP address allocation aswell as other functions. The PDN Gateway 172 and the BM-SC 170 areconnected to the IP Services 176. The IP Services 176 may include theInternet, an intranet, an IP Multimedia Subsystem (IMS), a PS StreamingService, and/or other IP services. The BM-SC 170 may provide functionsfor MBMS user service provisioning and delivery. The BM-SC 170 may serveas an entry point for content provider MBMS transmission, may be used toauthorize and initiate MBMS Bearer Services within a public land mobilenetwork (PLMN), and may be used to schedule MBMS transmissions. The MBMSGateway 168 may be used to distribute MBMS traffic to the base stations102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN)area broadcasting a particular service, and may be responsible forsession management (start/stop) and for collecting eMBMS relatedcharging information.

The 5GC 190 may include a Access and Mobility Management Function (AMF)192, other AMFs 193, a Session Management Function (SMF) 194, and a UserPlane Function (UPF) 195. The AMF 192 may be in communication with aUnified Data Management (UDM) 196. The AMF 192 can be a control nodethat processes the signaling between the UEs 104 and the 5GC 190.Generally, the AMF 192 can provide QoS flow and session management. UserInternet protocol (IP) packets (e.g., from one or more UEs 104) can betransferred through the UPF 195. The UPF 195 can provide UE IP addressallocation for one or more UEs, as well as other functions. The UPF 195is connected to the IP Services 197. The IP Services 197 may include theInternet, an intranet, an IP Multimedia Subsystem (IMS), a PS StreamingService, and/or other IP services.

The base station may also be referred to as a gNB, Node B, evolved NodeB (eNB), an access point, a base transceiver station, a radio basestation, a radio transceiver, a transceiver function, a basic serviceset (BSS), an extended service set (ESS), a transmit reception point(TRP), or some other suitable terminology. The base station 102 providesan access point to the EPC 160 or 5GC 190 for a UE 104. Examples of UEs104 include a cellular phone, a smart phone, a session initiationprotocol (SIP) phone, a laptop, a personal digital assistant (PDA), asatellite radio, a positioning system (e.g., satellite, terrestrial), amultimedia device, a video device, a digital audio player (e.g., MP3player), a camera, a game console, a tablet, a smart device, robots,drones, an industrial/manufacturing device, a wearable device (e.g., asmart watch, smart clothing, smart glasses, virtual reality goggles, asmart wristband, smart jewelry (e.g., a smart ring, a smart bracelet)),a vehicle/a vehicular device, a meter (e.g., parking meter, electricmeter, gas meter, water meter, flow meter), a gas pump, a large or smallkitchen appliance, a medical/healthcare device, an implant, asensor/actuator, a display, or any other similar functioning device.Some of the UEs 104 may be referred to as IoT devices (e.g., meters,pumps, monitors, cameras, industrial/manufacturing devices, appliances,vehicles, robots, drones, etc.). IoT UEs may include MTC/enhanced MTC(eMTC, also referred to as CAT-M, Cat M1) UEs, NB-IoT (also referred toas CAT NB1) UEs, as well as other types of UEs. In the presentdisclosure, eMTC and NB-IoT may refer to future technologies that mayevolve from or may be based on these technologies. For example, eMTC mayinclude FeMTC (further eMTC), eFeMTC (enhanced further eMTC), mMTC(massive MTC), etc., and NB-IoT may include eNB-IoT (enhanced NB-IoT),FeNB-IoT (further enhanced NB-IoT), etc. The UE 104 may also be referredto as a station, a mobile station, a subscriber station, a mobile unit,a subscriber unit, a wireless unit, a remote unit, a mobile device, awireless device, a wireless communications device, a remote device, amobile subscriber station, an access terminal, a mobile terminal, awireless terminal, a remote terminal, a handset, a user agent, a mobileclient, a client, or some other suitable terminology.

Turning now to FIGS. 2-7 , aspects are depicted with reference to one ormore components and one or more methods that may perform the actions oroperations described herein, where aspects in dashed line may beoptional. Although the operations described below in FIGS. 4-7 arepresented in a particular order and/or as being performed by an examplecomponent, it should be understood that the ordering of the actions andthe components performing the actions may be varied, depending on theimplementation. Moreover, it should be understood that the followingactions, functions, and/or described components may be performed by aspecially-programmed processor, a processor executingspecially-programmed software or computer-readable media, or by anyother combination of a hardware component and/or a software componentcapable of performing the described actions or functions.

Referring to FIG. 2 , one example of an implementation of UE 104 mayinclude a variety of components, some of which have already beendescribed above and are described further herein, including componentssuch as one or more processors 212 and memory 216 and transceiver 202 incommunication via one or more buses 244, which may operate inconjunction with modem 240 and/or communicating component 242 forperforming one or more HARQ processes 252 associated with multicastand/or unicast data transmissions. In some aspects, the one or more HARQprocesses may include one or more multicast HARQ processes 254 and/orone or more unicast HARQ processes 256.

In an aspect, the one or more processors 212 can include a modem 240and/or can be part of the modem 240 that uses one or more modemprocessors. Thus, the various functions related to communicatingcomponent 242 may be included in modem 240 and/or processors 212 and, inan aspect, can be executed by a single processor, while in otheraspects, different ones of the functions may be executed by acombination of two or more different processors. For example, in anaspect, the one or more processors 212 may include any one or anycombination of a modem processor, or a baseband processor, or a digitalsignal processor, or a transmit processor, or a receiver processor, or atransceiver processor associated with transceiver 202. In other aspects,some of the features of the one or more processors 212 and/or modem 240associated with communicating component 242 may be performed bytransceiver 202.

Also, memory 216 may be configured to store data used herein and/orlocal versions of applications 275 or communicating component 242 and/orone or more of its subcomponents being executed by at least oneprocessor 212. Memory 216 can include any type of computer-readablemedium usable by a computer or at least one processor 212, such asrandom access memory (RAM), read only memory (ROM), tapes, magneticdiscs, optical discs, volatile memory, non-volatile memory, and anycombination thereof. In an aspect, for example, memory 216 may be anon-transitory computer-readable storage medium that stores one or morecomputer-executable codes defining communicating component 242 and/orone or more of its subcomponents, and/or data associated therewith, whenUE 104 is operating at least one processor 212 to execute communicatingcomponent 242 and/or one or more of its subcomponents.

Transceiver 202 may include at least one receiver 206 and at least onetransmitter 208. Receiver 206 may include hardware and/or softwareexecutable by a processor for receiving data, the code comprisinginstructions and being stored in a memory (e.g., computer-readablemedium). Receiver 206 may be, for example, a radio frequency (RF)receiver. In an aspect, receiver 206 may receive signals transmitted byat least one base station 102. Additionally, receiver 206 may processsuch received signals, and also may obtain measurements of the signals,such as, but not limited to, Ec/Io, SNR, reference signal received power(RSRP), received signal strength indicator (RSSI), etc. Transmitter 208may include hardware and/or software executable by a processor fortransmitting data, the code comprising instructions and being stored ina memory (e.g., computer-readable medium). A suitable example oftransmitter 208 may including, but is not limited to, an RF transmitter.

Moreover, in an aspect, UE 104 may include RF front end 288, which mayoperate in communication with one or more antennas 265 and transceiver202 for receiving and transmitting radio transmissions, for example,wireless communications transmitted by at least one base station 102 orwireless transmissions transmitted by UE 104. RF front end 288 may beconnected to one or more antennas 265 and can include one or morelow-noise amplifiers (LNAs) 290, one or more switches 292, one or morepower amplifiers (PAs) 298, and one or more filters 296 for transmittingand receiving RF signals. The antennas 265 may include one or moreantennas, antenna elements, and/or antenna arrays.

In an aspect, LNA 290 can amplify a received signal at a desired outputlevel. In an aspect, each LNA 290 may have a specified minimum andmaximum gain values. In an aspect, RF front end 288 may use one or moreswitches 292 to select a particular LNA 290 and its specified gain valuebased on a desired gain value for a particular application.

Further, for example, one or more PA(s) 298 may be used by RF front end288 to amplify a signal for an RF output at a desired output powerlevel. In an aspect, each PA 298 may have specified minimum and maximumgain values. In an aspect, RF front end 288 may use one or more switches292 to select a particular PA 298 and its specified gain value based ona desired gain value for a particular application.

Also, for example, one or more filters 296 can be used by RF front end288 to filter a received signal to obtain an input RF signal. Similarly,in an aspect, for example, a respective filter 296 can be used to filteran output from a respective PA 298 to produce an output signal fortransmission. In an aspect, each filter 296 can be connected to aspecific LNA 290 and/or PA 298. In an aspect, RF front end 288 can useone or more switches 292 to select a transmit or receive path using aspecified filter 296, LNA 290, and/or PA 298, based on a configurationas specified by transceiver 202 and/or processor 212.

As such, transceiver 202 may be configured to transmit and receivewireless signals through one or more antennas 265 via RF front end 288.In an aspect, transceiver may be tuned to operate at specifiedfrequencies such that UE 104 can communicate with, for example, one ormore base stations 102 or one or more cells associated with one or morebase stations 102. In an aspect, for example, modem 240 can configuretransceiver 202 to operate at a specified frequency and power levelbased on the UE configuration of the UE 104 and the communicationprotocol used by modem 240.

In an aspect, modem 240 can be a multiband-multimode modem, which canprocess digital data and communicate with transceiver 202 such that thedigital data is sent and received using transceiver 202. In an aspect,modem 240 can be multiband and be configured to support multiplefrequency bands for a specific communications protocol. In an aspect,modem 240 can be multimode and be configured to support multipleoperating networks and communications protocols. In an aspect, modem 240can control one or more components of UE 104 (e.g., RF front end 288,transceiver 202) to enable transmission and/or reception of signals fromthe network based on a specified modem configuration. In an aspect, themodem configuration can be based on the mode of the modem and thefrequency band in use. In another aspect, the modem configuration can bebased on UE configuration information associated with UE 104 as providedby the network during cell selection and/or cell reselection.

In an aspect, the processor(s) 212 may correspond to one or more of theprocessors described in connection with the UE in FIG. 8 . Similarly,the memory 216 may correspond to the memory described in connection withthe UE in FIG. 8 .

Referring to FIG. 3 , one example of an implementation of base station102 (e.g., a base station 102 and/or gNB 180, as described above) mayinclude a variety of components, some of which have already beendescribed above, but including components such as one or more processors312 and memory 316 and transceiver 302 in communication via one or morebuses 344, which may operate in conjunction with modem 340 andretransmission component 342 for facilitating retransmissions accordingto one or more HARQ processes 252 via multicast and/or unicast datatransmissions. In some aspects, the one or more HARQ processes mayinclude one or more multicast HARQ processes 254 and/or one or moreunicast HARQ processes 256.

The transceiver 302, receiver 306, transmitter 308, one or moreprocessors 312, memory 316, applications 375, buses 344, RF front end388, LNAs 390, switches 392, filters 396, PAs 398, and one or moreantennas 365 may be the same as or similar to the correspondingcomponents of UE 104, as described above, but configured or otherwiseprogrammed for base station operations as opposed to UE operations.

In an aspect, the processor(s) 312 may correspond to one or more of theprocessors described in connection with the base station in FIG. 8 .Similarly, the memory 316 may correspond to the memory described inconnection with the base station in FIG. 8 .

FIG. 4 illustrates a flow chart of an example of a method 400 forwireless communication at a network entity. In an example, a basestation 102 can perform the functions described in method 400 using oneor more of the components described in FIGS. 1 and 3 .

At block 402, the method 400 may transmit first multicast data to aplurality of UEs on at least one downlink communication channel. In anaspect, the retransmission component 342, e.g., in conjunction withprocessor(s) 312, memory 316, and/or transceiver 302, may be configuredto transmit first multicast data to a plurality of UEs 104 on at leastone downlink communication channel. Thus, the network entity 102, theprocessor(s) 312, the determining component 342 or one of itssubcomponents may define the means for transmitting first multicast datato a plurality of UEs on at least one downlink communication channel.

At block 404, the method 400 may receive, on an uplink communicationchannel, a NACK from one or more UEs from the plurality of UEs inresponse to the multicast data transmission. In an aspect, theretransmission component 342, e.g., in conjunction with processor(s)312, memory 316, and/or transceiver 302, may be configured to receive,on an uplink communication channel, a NACK from one or more UEs 104 fromthe plurality of UEs in response to the multicast transmission. Thus,the network entity 102, the processor(s) 312, the determining component342 or one of its subcomponents may define the means for receiving, onan uplink communication channel, a NACK from one or more UEs from theplurality of UEs in response to the multicast transmission.

At block 406, the method 400 may transmit second multicast data,including at a portion of the first multicast data to the one or moreUEs according to a HARQ process. In an aspect, the retransmissioncomponent 342, e.g., in conjunction with processor(s) 312, memory 316,and/or transceiver 302, may be configured to transmit second multicastdata, including at a portion of the first multicast data to the one ormore UEs 104 according to a HARQ process. Thus, the network entity 102,the processor(s) 312, the determining component 342 or one of itssubcomponents may define the means for transmitting second multicastdata, including at a portion of the first multicast data to the one ormore UEs according to a HARQ process.

In some aspects, the plurality of UEs 104 may be associated with acommon G-RNTI.

Although not shown, in some aspects, the method 400 may includeconfiguring a number of HARQ processes for multicast data transmission(e.g., multicast HARQ processes 254) for each of the plurality of UEs,wherein the number of HARQ processes for multicast data transmission maybe common across each UE of the plurality of UEs 104.

Although not shown, in some aspects, the method 400 may includedetermining a total number of HARQ processes 252 including the number ofHARQ processes for multicast data transmission (e.g., multicast HARQprocesses 254) and a number of HARQ processes for unicast datatransmission (e.g., unicast HARQ processes 256), and transmitting thetotal number of HARQ processes 252 to at least one of the plurality ofUEs 104.

In some aspects, the total number of HARQ processes 252 may correspondto a HARQ threshold value limiting the number of configured HARQprocesses.

Although not shown, in some aspects, the method 400 may includedetermining a number of HARQ processes for unicast data transmission(e.g., unicast HARQ processes 256), where configuring the number of HARQprocesses for multicast data transmission (e.g., multicast HARQprocesses 254) for each of the plurality of UEs 104 may includeallocating the number of HARQ processes for multicast data transmission(e.g., multicast HARQ processes 254) from the number of HARQ processes(e.g., HARQ processes 252), and transmitting the number of HARQprocesses for unicast data transmission (e.g., unicast HARQ processes256) and the number of HARQ processes for multicast data transmission(e.g., multicast HARQ processes 254) to one or more of the plurality ofUEs 104.

In some aspects, transmitting the second multicast data to the one ormore UEs 104 according to the HARQ process may include determining thatat least one HARQ process for unicast data transmission (e.g., from theunicast HARQ processes 256) is available, and associating the at leastone HARQ process from the unicast data transmission to the secondmulticast data transmission.

Although not shown, in some aspects, the method 400 may includeconfiguring a NDI based on associating the at least one HARQ processfrom the unicast data transmission (e.g., unicast HARQ processes 256) tothe second multicast data transmission.

Although not shown, in some aspects, the method 400 may includetransmitting at least one of the NDI for the at least one HARQ processassociated with the second multicast data transmission, a grant for theat least one HARQ process associated with the second multicast datatransmission, or a HARQ process override identifier for the at least oneHARQ process associated with the second multicast data transmission.

FIG. 5 illustrates a flow chart of an example of a method 500 forwireless communications at a UE. In one example, a UE 104 can performthe functions described in method 500 using one or more of thecomponents described in FIGS. 1 and 2 .

At block 502, the method 500 may receive, on a downlink communicationchannel from a network entity, first multicast data from a networkentity. In an aspect, the communicating component 242, e.g., inconjunction with processor(s) 212, memory 216, and/or transceiver 202,may be configured to receive, on a downlink communication channel from anetwork entity, first multicast data from a network entity (e.g., basestation 102). Thus, the UE 104, the processor(s) 212, transceiver 202,the communicating component 242 or one of its subcomponents may definethe means for receiving, on a downlink communication channel from anetwork entity, first multicast data from a network entity.

At block 504, the method 500 may determine that at least a portion ofthe first multicast data has not been received. In an aspect, thecommunicating component 242, e.g., in conjunction with processor(s) 212,memory 216, and/or transceiver 202, may be configured to determine thatat least a portion of the first multicast data has not been received.Thus, the UE 104, the processor(s) 212, the communicating component 242or one of its subcomponents may define the means for determining that atleast a portion of the first multicast data has not been received.

At block 506, the method 500 may transmit, on an uplink communicationchannel to the network entity, a NACK to the network entity according toa HARQ process in response to determining that at least the portion ofthe first multicast data has not been received. In an aspect, thecommunicating component 242, e.g., in conjunction with processor(s) 212,memory 216, and/or transceiver 202, may be configured to transmit, on anuplink communication channel to the network entity, a NACK to thenetwork entity according to a HARQ process in response to determiningthat at least the portion of the first multicast data has not beenreceived. Thus, the UE 104, the processor(s) 212, transceiver 202, thecommunicating component 242 or one of its subcomponents may define themeans for transmitting, on an uplink communication channel to thenetwork entity, a NACK to the network entity according to a HARQ processin response to determining that at least the portion of the firstmulticast data has not been received.

At block 508, the method 500 may receive second multicast data includingat least the portion of the first multicast data according to the HARQprocess in response to transmitting the NACK to the network entity. Inan aspect, the communicating component 242, e.g., in conjunction withprocessor(s) 212, memory 216, and/or transceiver 202, may be configuredto receive second multicast data including at least the portion of thefirst multicast data according to the HARQ process in response totransmitting the NACK to the network entity. Thus, the UE 104, theprocessor(s) 212, transceiver 202, the communicating component 242 orone of its subcomponents may define the means for receiving secondmulticast data including at least the portion of the first multicastdata according to the HARQ process in response to transmitting the NACKto the network entity.

Although not shown, in some aspects, the method 500 may includereceiving a number of HARQ processes permitted for multicast datatransmission from the network entity.

Although not shown, in some aspects, the method 500 may includereceiving configuration of a number of HARQ processes for unicast (e.g.,unicast HARQ processes 256) and a number of HARQ processes for multicastdata transmission (e.g., multicast HARQ processes 256), where the numberof HARQ processes for unicast data transmission plus the number of HARQprocesses for multicast data transmission does not satisfy (e.g., isbelow) a threshold (e.g., HARQ processes 252 is below a threshold HARQvalue).

Although not shown, in some aspects, the method 500 may includereceiving a number of HARQ processes for unicast data transmission(e.g., unicast HARQ processes 256) including an allocation of the numberof HARQ processes for multicast data transmission (e.g., multicast HARQprocesses 254) from the number of HARQ processes for unicast datatransmission.

In some aspects, the HARQ process may correspond to one of the allocatednumber of HARQ processes for multicast data transmission from the numberof HARQ processes for unicast data transmission.

In some aspects, receiving the second multicast data of at least theportion of the data may include receiving the second multicast dataaccording to the HARQ process previously associated with a unicast datatransmission.

Although not shown, in some aspects, the method 500 may includereceiving at least one of a NDI for the HARQ process associated with thesecond multicast data, a grant for the HARQ process associated with thesecond multicast data transmission, or a HARQ process overrideidentifier for the HARQ process associated with the second multicastdata transmission.

In some aspects, reception of the grant may trigger clearing of astorage buffer and an indication of a toggling of the NDI.

In some aspects, the HARQ process identifier may indicate that the HARQprocess for multicast data transmission overrides the HARQ process forunicast data transmission.

FIG. 6 illustrates a flow chart of an example of a method 600 forwireless communication at a network entity. In an example, a basestation 102 can perform the functions described in method 600 using oneor more of the components described in FIGS. 1 and 3 .

At block 602, the method 600 may transmit multicast data to a pluralityof UEs on at least one downlink communication channel. In an aspect, theretransmission component 342, e.g., in conjunction with processor(s)312, memory 316, and/or transceiver 302, may be configured to transmitmulticast data to a plurality of UEs 104 on at least one downlinkcommunication channel. Thus, the network entity 102, the processor(s)312, the transceiver 302, the determining component 342 or one of itssubcomponents may define the means for transmitting multicast data to aplurality of UEs on at least one downlink communication channel.

At block 604, the method 600 may receive, on an uplink communicationchannel, a NACK from one or more UEs from the plurality of UEs inresponse to the multicast data transmission. In an aspect, theretransmission component 342, e.g., in conjunction with processor(s)312, memory 316, and/or transceiver 302, may be configured to receive,on an uplink communication channel, a NACK from one or more UEs 104 fromthe plurality of UEs in response to the multicast data transmission.Thus, the network entity 102, the transceiver 302, the processor(s) 312,the determining component 342 or one of its subcomponents may define themeans for receiving, on an uplink communication channel, a NACK from oneor more UEs from the plurality of UEs in response to the multicast datatransmission.

At block 606, the method 600 may transmit unicast data, including at aportion of the data to the one or more UEs according to a HARQ processto the at least one UE. In an aspect, the retransmission component 342,e.g., in conjunction with processor(s) 312, memory 316, and/ortransceiver 302, may be configured to transmit unicast data, includingat a portion of the data to the one or more UEs 104 according to a HARQprocess to the at least one UE. Thus, the network entity 102, theprocessor(s) 312, the transceiver 302, the determining component 342 orone of its subcomponents may define the means for transmitting unicastdata, including at a portion of the multicast data to the one or moreUEs according to a HARQ process to the at least one UE.

Although not shown, in some aspects, the method 600 may includetransmitting a grant associated with a C-RNTI indicating a HARQ processidentifier for unicast data transmission including the HARQ process,where the HARQ process identifier for unicast data transmission isassociated with at least one HARQ process for multicast datatransmission.

In some aspects, a subset of the number of HARQ processes for unicastdata transmission (e.g., unicast HARQ processes 256) may be allocatedfor the multicast data transmission.

Although not shown, in some aspects, the method 600 may includetransmitting a grant associated with a RETX-RNTI indicating the unicastdata transmission is associated with DCI of the multicast datatransmission.

Although not shown, in some aspects, the method 600 may includetransmitting a grant for the unicast data transmission based on a G-RNTIand DCI mapped to a UE-specific search space.

In some aspects, receiving the NACK from the at least one UE may includereceiving a first NACK from a first UE and a second NACK from a secondUE, the method 600 may further include transmit a plurality of grants tothe first UE and the second UE within a single TTI, where retransmittingat least the portion of the data includes retransmitting to the first UEaccording to the HARQ process via unicast data transmission and thesecond UE according to a second HARQ process via unicast datatransmission.

In some aspects, receiving the NACK from the at least one UE may includereceiving a first NACK from a first UE and a second NACK from a secondUE, the method further including transmitting a grant to the first UEand the second UE within a second TTI, where the grant indicates aresource allocation with a plurality of clusters, wherein at least oneof MCS determination, TBS determination, or rate matching is performedindependently for each of the plurality of clusters.

FIG. 7 illustrates a flow chart of an example of a method 700 forwireless communications at a UE. In one example, a UE 104 can performthe functions described in method 700 using one or more of thecomponents described in FIGS. 1 and 2 .

At block 702, the method 700 may receive, on a downlink communicationchannel from a network entity, first multicast data from a networkentity. In an aspect, the communicating component 242, e.g., inconjunction with processor(s) 212, memory 216, and/or transceiver 202,may be configured to receive, on a downlink communication channel from anetwork entity, first multicast data from a network entity (e.g., basestation 102). Thus, the UE 104, the processor(s) 212, transceiver 202,the communicating component 242 or one of its subcomponents may definethe means for receiving, on a downlink communication channel from anetwork entity, first multicast data from a network entity.

At block 704, the method 700 may determine that at least a portion ofthe multicast data has not been received via multicast datatransmission. In an aspect, the communicating component 242, e.g., inconjunction with processor(s) 212, memory 216, and/or transceiver 202,may be configured to determine that at least a portion of the multicastdata has not been received via multicast data transmission. Thus, the UE104, the processor(s) 212, transceiver 202, the communicating component242 or one of its subcomponents may define the means for determiningthat at least a portion of the multicast data has not been received viamulticast data transmission.

At block 706, the method 700 may transmit, on an uplink communicationchannel to the network entity, a NACK to the network entity according toa HARQ process in response to determining that at least the multicastportion has not been received. In an aspect, the communicating component242, e.g., in conjunction with processor(s) 212, memory 216, and/ortransceiver 202, may be configured to transmit, on an uplinkcommunication channel to the network entity, a NACK to the networkentity according to a HARQ process in response to determining that atleast the portion of the multicast data has not been received. Thus, theUE 104, the processor(s) 212, transceiver 202, the communicatingcomponent 242 or one of its subcomponents may define the means fortransmitting, on an uplink communication channel to the network entity,a NACK to the network entity according to a HARQ process in response todetermining that at least the portion of the multicast data has not beenreceived.

At block 708, the method 700 may receive unicast data including at leastthe portion of the multicast data according to the HARQ process and inresponse to transmitting the NACK to the network entity. In an aspect,the communicating component 242, e.g., in conjunction with processor(s)212, memory 216, and/or transceiver 202, may be configured to receiveunicast data including at least the portion of the multicast dataaccording to the HARQ process and in response to transmitting the NACKto the network entity. Thus, the UE 104, the processor(s) 212,transceiver 202, the communicating component 242 or one of itssubcomponents may define the means for receiving unicast data includingat least the portion of the multicast data according to the HARQ processand in response to transmitting the NACK to the network entity.

Although not shown, in some aspects, the method 700 may includereceiving a grant associated with a C-RNTI indicating a HARQ processidentifier for unicast data transmission including the HARQ process,wherein the HARQ process identifier for unicast data transmission isassociated with at least one HARQ process for multicast datatransmission.

In some aspects, a subset of the number of HARQ processes for unicastdata transmission is allocated for the multicast data transmission.

In some aspects, the multicast data transmission is associated with afirst LLR and the unicast data retransmission is associated with asecond LLR, the method 700 further including combining the first LLR andthe second LLR in response to receiving the unicast data including atleast the portion of the data.

Although not shown, in some aspects, the method 700 receiving a grantassociated with a RETX-RNTI indicating the unicast data retransmissionis associated with DCI of the multicast data transmission.

Although not shown, in some aspects, the method 700 may includereceiving a grant for the unicast data retransmission based on a G-RNTand DCI mapped to a UE-specific search space.

Although not shown, in some aspects, the method 700 receiving aplurality of grants within a single TTI, and determining a grantassociated with a G-RNTI of the UE from the grants within the TTI basedat least on one of a DMRS SNR, a UE capability indication within DCI, orDCI for a UE cluster including the UE, and where receiving the unicastretransmission includes receiving the unicast data transmission of atleast the portion of the data according to the HARQ process based ondetermining the grant associated with the G-RNTI of the UE.

FIG. 8 is a block diagram of a MIMO communication system 800 including abase station 102 and a UE 104. The MIMO communication system 800 mayillustrate aspects of the wireless communication access network 100described with reference to FIG. 1 . The base station 102 may be anexample of aspects of the base station 102 described with reference toFIG. 1 . The base station 102 may be equipped with antennas 834 and 835,and the UE 104 may be equipped with antennas 852 and 853. In the MIMOcommunication system 800, the base station 102 may be able to send dataover multiple communication links at the same time. Each communicationlink may be called a “layer” and the “rank” of the communication linkmay indicate the number of layers used for communication. For example,in a 2×2 MIMO communication system where base station 102 transmits two“layers,” the rank of the communication link between the base station102 and the UE 104 is two.

At the base station 102, a transmit (Tx) processor 820 may receive datafrom a data source. The transmit processor 820 may process the data. Thetransmit processor 820 may also generate control symbols or referencesymbols. A transmit MIMO processor 830 may perform spatial processing(e.g., precoding) on data symbols, control symbols, or referencesymbols, if applicable, and may provide output symbol streams to thetransmit modulator/demodulators 832 and 833. Each modulator/demodulator832 through 833 may process a respective output symbol stream (e.g., forOFDM, etc.) to obtain an output sample stream. Eachmodulator/demodulator 832 through 833 may further process (e.g., convertto analog, amplify, filter, and upconvert) the output sample stream toobtain a DL signal. In one example, DL signals frommodulator/demodulators 832 and 833 may be transmitted via the antennas834 and 835, respectively.

The UE 104 may be an example of aspects of the UEs 104 described withreference to FIGS. 1 and 2 . At the UE 104, the UE antennas 852 and 853may receive the DL signals from the base station 102 and may provide thereceived signals to the modulator/demodulators 854 and 855,respectively. Each modulator/demodulator 854 through 855 may condition(e.g., filter, amplify, downconvert, and digitize) a respective receivedsignal to obtain input samples. Each modulator/demodulator 854 through855 may further process the input samples (e.g., for OFDM, etc.) toobtain received symbols. A MIMO detector 856 may obtain received symbolsfrom the modulator/demodulators 854 and 855, perform MIMO detection onthe received symbols, if applicable, and provide detected symbols. Areceive (Rx) processor 858 may process (e.g., demodulate, deinterleave,and decode) the detected symbols, providing decoded data for the UE 104to a data output, and provide decoded control information to a processor880, or memory 1182.

The processor 880 may in some cases execute stored instructions toinstantiate a communicating component 242 (see e.g., FIGS. 1 and 2 ).

On the uplink (UL), at the UE 104, a transmit processor 864 may receiveand process data from a data source. The transmit processor 864 may alsogenerate reference symbols for a reference signal. The symbols from thetransmit processor 864 may be precoded by a transmit MIMO processor 866if applicable, further processed by the modulator/demodulators 854 and855 (e.g., for SC-FDMA, etc.), and be transmitted to the base station102 in accordance with the communication parameters received from thebase station 102. At the base station 102, the UL signals from the UE104 may be received by the antennas 834 and 835, processed by themodulator/demodulators 832 and 833, detected by a MIMO detector 836 ifapplicable, and further processed by a receive processor 838. Thereceive processor 838 may provide decoded data to a data output and tothe processor 840 or memory 842.

The processor 840 may in some cases execute stored instructions toinstantiate a retransmission component 342 (see e.g., FIGS. 1 and 3 ).

The components of the UE 104 may, individually or collectively, beimplemented with one or more ASICs adapted to perform some or all of theapplicable functions in hardware. Each of the noted modules may be ameans for performing one or more functions related to operation of theMIMO communication system 800. Similarly, the components of the basestation 102 may, individually or collectively, be implemented with oneor more ASICs adapted to perform some or all of the applicable functionsin hardware. Each of the noted components may be a means for performingone or more functions related to operation of the MIMO communicationsystem 800.

Some Further Examples

In one example, a method of communications at a network entity comprisestransmitting first multicast data a plurality of UEs on at least onedownlink communication channel, receiving, on an uplink communicationchannel, a NACK from one or more UEs from the plurality of UEs inresponse to the first multicast data transmission, and transmittingsecond multicast data including at least a portion of the data to theone or more UEs according to a HARQ process.

One or more of the above examples can further include wherein theplurality of UEs are associated with a common G-RNTI.

One or more of the above examples can further include configuring anumber of HARQ processes for multicast data transmission for each of theplurality of UEs, wherein the number of HARQ processes is common acrosseach UE of the plurality of UEs.

One or more of the above examples can further include further comprisingdetermining a total number of HARQ processes including the number ofHARQ processes for multicast data transmission and a number of HARQprocesses for unicast data transmission, and transmitting the totalnumber of HARQ processes to at least one of the plurality of UEs.

One or more of the above examples can further include wherein the totalnumber of HARQ processes corresponds to a HARQ threshold value limitingthe number of configured HARQ processes.

One or more of the above examples can further include determining anumber of HARQ processes for unicast data transmission, whereinconfiguring the number of HARQ processes for multicast data transmissionfor each of the plurality of UEs includes allocating the number of HARQprocesses for multicast data transmission from the number of HARQprocesses, and transmitting the number of HARQ processes for unicastdata transmission and the number of HARQ processes for multicast datatransmission to one or more of the plurality of UEs.

One or more of the above examples can further include whereintransmitting the second multicast data to the one or more UEs accordingto the HARQ process includes determining that at least one HARQ processfor unicast data transmission is available, and associating the at leastone HARQ process from the unicast data transmission to the secondmulticast data transmission.

One or more of the above examples can further include configuring a NDIbased on associating the at least one HARQ process from the unicast datatransmission to the second multicast data transmission.

One or more of the above examples can further include transmitting atleast one of the NDI for the at least one HARQ process associated withthe second multicast data transmission, a grant for the at least oneHARQ process associated with the second multicast data transmission, ora HARQ process override identifier for the at least one HARQ processassociated with the second multicast data transmission.

In another example, a method of communications at a UE comprisesreceiving, on a downlink communication channel from a network entity,first multicast data from a network entity, determining that at least aportion of data from the first multicast data has not been received,transmitting, on an uplink communication channel to the network entity,a NACK to the network entity according to a HARQ process and in responseto determining that at least the portion of the data has not beenreceived, and receiving second multicast data including at least theportion of the data according to the HARQ process and in response totransmitting the NACK to the network entity.

One or more of the above examples can further include receiving a numberof HARQ processes permitted for multicast data transmission from thenetwork entity.

One or more of the above examples can further include receivingconfiguration of a number of HARQ processes for unicast and a number ofHARQ processes for multicast data transmission, wherein the number ofHARQ processes for unicast data transmission plus the number of HARQprocesses for multicast data transmission is below a threshold.

One or more of the above examples can further include receiving a numberof HARQ processes for unicast data transmission including an allocationof the number of HARQ processes for multicast data transmission from thenumber of HARQ processes for unicast data transmission.

One or more of the above examples can further include wherein the HARQprocess corresponds to one of the allocated number of HARQ processes formulticast data transmission from the number of HARQ processes forunicast data transmission.

One or more of the above examples can further include wherein receivingthe second multicast data of at least the portion of the data includesreceiving the second multicast data according to the HARQ processpreviously associated with a unicast data transmission.

One or more of the above examples can further include receiving at leastone of a NDI for the HARQ process associated with the second multicastdata a grant for the HARQ process associated with the second multicastdata transmission, or a HARQ process override identifier for the HARQprocess associated with the second multicast data transmission.

One or more of the above examples can further include wherein receptionof the grant triggers clearing of a storage buffer and an indication ofa toggling of the NDI.

One or more of the above examples can further include wherein the HARQprocess identifier indicates that the HARQ process for multicast datatransmission overrides the HARQ process for unicast data transmission.

In an additional example, a method of communications at a networkentity, comprises transmitting multicast data to a plurality of UEs onat least one downlink communication channel, receiving, on an uplinkcommunication channel, a NACK from at least one UE of the plurality ofUEs in response to the multicast data transmission, and transmittingunicast data including at least a portion of the data according to aHARQ process to the at least one UE.

One or more of the above examples can further include transmitting agrant associated with a C-RNTI indicating a HARQ process identifier forunicast data transmission including the HARQ process, wherein the HARQprocess identifier for unicast data transmission is associated with atleast one HARQ process for multicast data transmission.

One or more of the above examples can further include wherein a subsetof the number of HARQ processes for unicast data transmission isallocated for the multicast data transmission.

One or more of the above examples can further include transmitting agrant associated with a RETX-RNTI indicating the unicast datatransmission is associated with DCI of the multicast data transmission.

One or more of the above examples can further include transmitting agrant for the unicast data transmission based on a G-RNTI and DCI mappedto a UE-specific search space.

One or more of the above examples can further include wherein receivingthe NACK from the at least one UE includes receiving a first NACK from afirst UE and a second NACK from a second UE, the method furthercomprising transmitting a plurality of grants to the first UE and thesecond UE within a single TTI, wherein retransmitting at least theportion of the data includes retransmitting to the first UE according tothe HARQ process via unicast data transmission and the second UEaccording to a second HARQ process via unicast data transmission.

One or more of the above examples can further include wherein receivingthe NACK from the at least one UE includes receiving a first NACK from afirst UE and a second NACK from a second UE, the method furthercomprising transmitting a grant to the first UE and the second UE withina second TTI, wherein the grant indicates a resource allocation with aplurality of clusters, wherein at least one of MCS determination, TBSdetermination, or rate matching is performed independently for each ofthe plurality of clusters.

In yet another example, a method of communications at a UE comprisesreceiving, on a downlink communication channel from a network entity,multicast data from a network entity, determining that at least aportion of the data from the multicast data has not been received viathe multicast data transmission, transmitting, on an uplinkcommunication channel to the network entity, a NACK to the networkentity according to a HARQ process and in response to determining thatat least the portion of the data has not been received, and receivingunicast data including at least the portion of the data according to theHARQ process and in response to transmitting the NACK to the networkentity.

One or more of the above examples can further include receiving a grantassociated with a C-RNTI indicating a HARQ process identifier forunicast data transmission including the HARQ process, wherein the HARQprocess identifier for unicast data transmission is associated with atleast one HARQ process for multicast data transmission.

One or more of the above examples can further include wherein a subsetof the number of HARQ processes for unicast data transmission isallocated for the multicast data transmission.

One or more of the above examples can further include wherein themulticast data transmission is associated with a first LLR and theunicast data retransmission is associated with a second LLR, the methodfurther comprising combining the first LLR and the second LLR inresponse to receiving the unicast data including at least the portion ofthe data.

One or more of the above examples can further include receiving a grantassociated with a RETX-RNTI indicating the unicast data retransmissionis associated with DCI of the multicast data transmission.

One or more of the above examples can further include receiving a grantfor the unicast data retransmission based on a G-RNTI and DCI mapped toa UE-specific search space.

One or more of the above examples can further include receiving aplurality of grants within a single TTI, and determining a grantassociated with a G-RNTI of the UE from the grants within the TTI basedat least on one of a DMRS SNR, a UE capability indication within DCI, orDCI for a UE cluster including the UE, and wherein receiving the unicastdata retransmission includes receiving the unicast transmission of atleast the portion of the data according to the HARQ process based ondetermining the grant associated with the G-RNTI of the UE.

The above detailed description set forth above in connection with theappended drawings describes examples and does not represent the onlyexamples that may be implemented or that are within the scope of theclaims. The term “example,” when used in this description, means“serving as an example, instance, or illustration,” and not “preferred”or “advantageous over other examples.” The detailed description includesspecific details for the purpose of providing an understanding of thedescribed techniques. These techniques, however, may be practicedwithout these specific details. In some instances, well-known structuresand apparatuses are shown in block diagram form in order to avoidobscuring the concepts of the described examples.

Information and signals may be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that may bereferenced throughout the above description may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, computer-executable code or instructionsstored on a computer-readable medium, or any combination thereof.

The various illustrative blocks and components described in connectionwith the disclosure herein may be implemented or performed with aspecially-programmed device, such as but not limited to a processor, adigital signal processor (DSP), an ASIC, a FPGA or other programmablelogic device, a discrete gate or transistor logic, a discrete hardwarecomponent, or any combination thereof designed to perform the functionsdescribed herein. A specially-programmed processor may be amicroprocessor, but in the alternative, the processor may be anyconventional processor, controller, microcontroller, or state machine. Aspecially-programmed processor may also be implemented as a combinationof computing devices, e.g., a combination of a DSP and a microprocessor,multiple microprocessors, one or more microprocessors in conjunctionwith a DSP core, or any other such configuration.

The functions described herein may be implemented in hardware, software,or any combination thereof. If implemented in software executed by aprocessor, the functions may be stored on or transmitted over as one ormore instructions or code on a non-transitory computer-readable medium.Other examples and implementations are within the scope and spirit ofthe disclosure and appended claims. For example, due to the nature ofsoftware, functions described above can be implemented using softwareexecuted by a specially programmed processor, hardware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations. Moreover, the term “or” is intended to mean an inclusive “or”rather than an exclusive “or.” That is, unless specified otherwise, orclear from the context, the phrase, for example, “X employs A or B” isintended to mean any of the natural inclusive permutations. That is, forexample the phrase “X employs A or B” is satisfied by any of thefollowing instances: X employs A; X employs B; or X employs both A andB. Also, as used herein, including in the claims, “or” as used in a listof items prefaced by “at least one of” indicates a disjunctive list suchthat, for example, a list of “at least one of A, B, or C” means A or Bor C or AB or AC or BC or ABC (A and B and C).

Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage medium may be anyavailable medium that can be accessed by a general purpose or specialpurpose computer. By way of example, and not limitation,computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium that can be used to carry or store desiredprogram code means in the form of instructions or data structures andthat can be accessed by a general-purpose or special-purpose computer,or a general-purpose or special-purpose processor. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,include compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above are also included within the scope ofcomputer-readable media.

The previous description of the disclosure is provided to enable aperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the common principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Furthermore, although elements of the describedaspects and/or embodiments may be described or claimed in the singular,the plural is contemplated unless limitation to the singular isexplicitly stated. Additionally, all or a portion of any aspect and/orembodiment may be utilized with all or a portion of any other aspectand/or embodiment, unless stated otherwise. Thus, the disclosure is notto be limited to the examples and designs described herein but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A method of communications at a user equipment(UE), comprising: receiving, on a downlink communication channel from anetwork entity and based at least in part on a first identifierassociated with the UE, a multicast data transmission comprising firstmulticast data; identifying that at least a portion of the firstmulticast data has not been received; transmitting, on an uplinkcommunication channel to the network entity, a negative acknowledgment(NACK) according to a first hybrid automatic repeat request (HARQ)process based on identifying that at least the portion of the firstmulticast data has not been received; receiving, on a downlinkcommunication channel from the network entity and based at least in parton a second identifier associated with the UE and different from thefirst identifier, a unicast data transmission comprising unicast data,the unicast data transmission using a HARQ process identifier associatedwith the first HARQ process and different from the first identifier andthe second identifier, wherein the unicast data includes at least theportion of the first multicast data; and combining the first multicastdata and the unicast data.
 2. The method of claim 1, further comprisingreceiving a number of HARQ processes permitted for multicast datatransmission from the network entity.
 3. The method of claim 1, furthercomprising receiving a configuration of a number of HARQ processes forunicast data transmission and a number of HARQ processes for multicastdata transmission, wherein the number of HARQ processes for unicast datatransmission plus the number of HARQ processes for multicast datatransmission is below a threshold.
 4. The method of claim 1, furthercomprising receiving a number of HARQ processes for unicast datatransmission including an allocated number of HARQ processes formulticast data transmission from the number of HARQ processes forunicast data transmission.
 5. The method of claim 4, wherein the firstHARQ process corresponds to one of the allocated number of HARQprocesses for multicast data transmission from the number of HARQprocesses for unicast data transmission.
 6. The method of claim 1,wherein receiving the unicast data that includes at least the portion ofthe first multicast data includes receiving the unicast data accordingto the first HARQ process.
 7. The method of claim 1, further comprisingreceiving at least one of: a new data indicator (NDI) for the first HARQprocess associated with the unicast data, or a grant for the first HARQprocess associated with the unicast data transmission.
 8. The method ofclaim 7, wherein reception of the grant triggers clearing of a storagebuffer and an indication of a toggling of the NDI.
 9. The method ofclaim 1, wherein the first identifier associated with the UE is a groupradio network temporary identifier (G-RNTI), and wherein secondidentifier associated with the UE is a cell radio network temporaryidentifier (C-RNTI).
 10. The method of claim 1, wherein the firstidentifier associated with the UE is a group radio network temporaryidentifier (G-RNTI), and wherein second identifier associated with theUE is a retransmission radio network temporary identifier (RETX-RNTI)indicating the unicast data transmission is a retransmission associatedwith downlink control information (DCI) of the multicast datatransmission.
 11. An apparatus for wireless communication, comprising: atransceiver; a memory configured to store instructions; and at least oneprocessor communicatively coupled with the transceiver and the memory,wherein the at least one processor is configured to cause the apparatusto: receive, on a downlink communication channel from a network entityand based at least in part on a first identifier associated with theapparatus, a multicast data transmission comprising first multicastdata; identify that at least a portion of the first multicast data hasnot been received; transmit, on an uplink communication channel to thenetwork entity, a negative acknowledgment (NACK) according to a firsthybrid automatic repeat request (HARQ) process based on identifying thatat least the portion of the first multicast data has not been received;receive, on a downlink communication channel from the network entity andbased at least in part on a second identifier associated with theapparatus and different from the first identifier, a unicast datatransmission comprising unicast data, the unicast data transmissionusing a HARQ process identifier associated with the first HARQ processand different from the first identifier and the second identifier,wherein the unicast data includes at least the portion of the firstmulticast data; and combine the first multicast data and the unicastdata.
 12. The apparatus of claim 11, wherein the at least one processoris configured to receive a number of HARQ processes permitted formulticast data transmission from the network entity.
 13. The apparatusof claim 11, wherein the at least one processor is configured to receivea configuration of a number of HARQ processes for unicast datatransmission and a number of HARQ processes for multicast datatransmission, and wherein the number of HARQ processes for unicast datatransmission plus the number of HARQ processes for multicast datatransmission is below a threshold.
 14. The apparatus of claim 11,wherein the at least one processor is configured to receive a number ofHARQ processes for unicast data transmission including an allocatednumber of HARQ processes for multicast data transmission from the numberof HARQ processes for unicast data transmission.
 15. The apparatus ofclaim 14, wherein the first HARQ process corresponds to one of theallocated number of HARQ processes for multicast data transmission fromthe number of HARQ processes for unicast data transmission.
 16. Theapparatus of claim 11, wherein the at least one processor is configuredto receive the unicast data transmission according to the first HARQprocess.
 17. The apparatus of claim 16, wherein the at least oneprocessor is further configured to receive at least one of: a new dataindicator (NDI) for the first HARQ process associated with the unicastdata transmission, or a grant for the first HARQ process associated withthe unicast data transmission.
 18. The apparatus of claim 17, whereinreception of the grant triggers clearing of a storage buffer and anindication of a toggling of the NDI.
 19. The apparatus of claim 11,wherein the first identifier associated with the apparatus is a groupradio network temporary identifier (G-RNTI), and wherein secondidentifier associated with the apparatus is a cell radio networktemporary identifier (C-RNTI).
 20. The apparatus of claim 11, whereinthe first identifier associated with the apparatus is a group radionetwork temporary identifier (G-RNTI), and wherein second identifierassociated with the apparatus is a retransmission radio networktemporary identifier (RETX-RNTI) indicating the unicast datatransmission is a retransmission associated with downlink controlinformation (DCI) of the multicast data transmission.
 21. A method ofcommunications at a user equipment (UE), comprising: receiving, on adownlink communication channel from a network entity and based at leastin part on a first identifier associated with the UE, a multicast datatransmission comprising first multicast data; identifying that at leasta portion of the first multicast data has not been received via themulticast data transmission; transmitting, on an uplink communicationchannel to the network entity, a negative acknowledgment (NACK)according to a first hybrid automatic repeat request (HARQ) processbased on identifying that at least the portion of the first multicastdata has not been received; receiving a grant for a unicast dataretransmission based on a group radio network temporary identifier(G-RNTI) and downlink control information (DCI) mapped to a UE-specificsearch space; and receiving, on a downlink communication channel fromthe network entity and based on transmitting the NACK, a unicast dataretransmission comprising unicast data that includes at least theportion of the first multicast data, the unicast data retransmissionusing the first HARQ process.
 22. The method of claim 21, furthercomprising receiving another grant associated with a cell radio networktemporary identifier (C-RNTI) indicating a HARQ process identifier forunicast data transmission including the first HARQ process, wherein theHARQ process identifier for unicast data transmission is associated withat least one HARQ process for multicast data transmission, wherein asubset of a number of HARQ processes for unicast data transmission isallocated for the multicast data transmission.
 23. The method of claim22, wherein the multicast data transmission is associated with a firstlog-likelihood ratio (LLR) and the unicast data transmission isassociated with a second LLR, the method further comprising: combiningthe first LLR and the second LLR in response to receiving the unicastdata including at least the portion of the first multicast data.
 24. Themethod of claim 21, further comprising receiving another grantassociated with a retransmission radio network temporary identifier(RETX-RNTI) indicating the unicast data retransmission is associatedwith downlink control information (DCI) of the multicast datatransmission.
 25. The method of claim 21, further comprising: receivinga plurality of grants within a single transmission time interval (TTI);and identifying a grant associated with a G-RNTI of the UE from thegrants within the TTI based at least on one of: a demodulation referencesignal (DMRS) signal-to-noise ratio (SNR), a UE capability indicationwithin downlink control information (DCI), or DCI for a UE clusterincluding the UE, and wherein receiving the unicast data retransmissionincludes receiving the unicast data transmission of at least the portionof the first multicast data according to the first HARQ process based ondetermining the grant associated with the G-RNTI of the UE.
 26. Anapparatus of communications at a user equipment (UE), comprising: atransceiver; a memory configured to store instructions; and at least oneprocessor communicatively coupled with the transceiver and the memory,wherein the at least one processor is configured to cause the apparatusto: receive, on a downlink communication channel from a network entityand based at least in part on a first identifier associated with the UE,a multicast data transmission comprising first multicast data; identifythat at least a portion of the first multicast data has not beenreceived via the multicast data transmission; transmit, on an uplinkcommunication channel to the network entity, a negative acknowledgment(NACK) according to a first hybrid automatic repeat request (HARQ)process based on identifying that at least the portion of the firstmulticast data has not been received; receive a grant for a unicast dataretransmission based on a group radio network temporary identifier(G-RNTI) and downlink control information (DCI) mapped to a UE-specificsearch space; and receive, on a downlink communication channel from thenetwork entity and based on transmitting the NACK, a unicast dataretransmission comprising unicast data that includes at least theportion of the first multicast data, the unicast data retransmissionusing the first HARQ process.
 27. The apparatus of claim 26, wherein theat least one processor is further configured to receive another grantassociated with a cell radio network temporary identifier (C-RNTI)indicating a HARQ process identifier for unicast data transmissionincluding the first HARQ process, wherein the HARQ process identifierfor unicast data transmission is associated with at least one HARQprocess for multicast data transmission, wherein a subset of a number ofHARQ processes for unicast data transmission is allocated for themulticast data transmission.
 28. The apparatus of claim 27, wherein themulticast data transmission is associated with a first log-likelihoodratio (LLR) and the unicast data transmission is associated with asecond LLR, and wherein the at least one processor is further configuredto: combine the first LLR and the second LLR in response to receivingthe unicast data including at least the portion of the first multicastdata.
 29. The apparatus of claim 26, wherein the at least one processoris further configured to receive another grant associated with aretransmission radio network temporary identifier (RETX-RNTI) indicatingthe unicast data retransmission is associated with downlink controlinformation (DCI) of the multicast data transmission.
 30. The apparatusof claim 26, wherein the at least one processor is further configuredto: receive a plurality of grants within a single transmission timeinterval (TTI); and identify a grant associated with a G-RNTI of the UEfrom the grants within the TTI based at least on one of: a demodulationreference signal (DMRS) signal-to-noise ratio (SNR), a UE capabilityindication within downlink control information (DCI), or DCI for a UEcluster including the UE, and wherein to receive the unicast dataretransmission, the at least one processor is further configured toreceive the unicast data transmission of at least the portion of thefirst multicast data according to the first HARQ process based ondetermining the grant associated with the G-RNTI of the UE.